Method of making sponge iron



Oct. 2, 1945. E, A, STEWART 2,386,072

METHOD oF MAKING sPoNGE IRON Filed'Feb. 28, 1944 z Sheets-sheet 1 E. A, STEWART med rabyzs; '1944 METHOD OF MAKING SPO Enos Si'ewari' Patented Oct. 2, 1945 METHOD F MAKING SPON GE IRON Enos A. Stewart, Canton, Ohio Application February 28, 1944,'Seriai No. 524,161

(Cl. 'J5-33) 9' Claims.

The invention relates to the reduction of metallic ores and oxides, and is more particularly concerned with the reduction of the various iron ores and ,oxides to produce sponge iron.

The invention has for its object the'reducton of iron ores or oxides by a novel and simple method which consists in finely dividing the ores or oxides and mixing them only with a sumcient amount of a binder, such as a starch solution, and forming the mixture into a compact mass, as by extruding it through a die or pressing it in a mold to form a compact, compressed` block or briquette of such thickness that heat will entirely penetrate directly through all portions thereof, so as to substantially entirely reduce vthe ores or oxides, placing the block or briquette within a sagger or similar receptacle, lling the sagger and entirely surrounding the block or briquette of ores or oxides with powdered carbonaceous material, and subjecting it to a suiiiciently high temperature for a, suill'cient period of time to entirely reduce the ores or oxides producing a solid briquette or block of metallic iron.

It is a further object of the invention to provide for the reduction of iron ores or oxides by mixing finely divided ores or oxides with a suit-A able binder and extruding, molding or pressing the mixture into the form of a hollow briquette or block, placing the hollow formed article with in a sagger or similar receptacle, filling the sagger and the opening or openings within the briquette with powdered coal or coke, and subjecting it to a sufficiently high temperature for a suilcient period of time to reduce the ores or oxides, producing a hollow briquette or block of sponge iron which may be easily handled and transported.

Another object is to provide for covering the upper open end of each sagger so that even though they arefired in an oxidizing atmosphere the ore or oxide brlquette or block will be maintained under a reducing atmosphere since it is entirely enclosed and surrounded by the powdered carbonaceous, reducing material.

A further object of the invention is to provide a hollow briquette or block of ores or oxides all of the walls of which are the heat from the burning carbonaceous material on each side of each Wall will entirely penetrate all portions of the briquette so as to completely reduce the ores or oxides.

A still further object is the provision of a process for the reduction of the natural .iron ores such as hematite, limonite, magnetite, siderite,

of such thickness that,

gothite, tungite, bog ores and the like, or iron oxides such as mill scale, flue dust, or other material containing appreciable amounts of ferric hollowbriquette or block oxide (FezOa), ferroso-ferric oxide (FesOi), or ferrous oxide (FeO) which consists in mixing the ores or oxides with a small amount oi' a suitable binder, such as a starch solution, extruding, molding or pressing the mixture into a hollow briquette or block, drying the formed article, then placing it within a sagger or the like and completely filling the sagger and the opening or openings in the briquette with powdered coal or coke, and subjecting it to a temperature ofabout 2D00 F. for a period of several-hours to reduce the ores or oxides to a sponge iron briquette.

Another object is to provide a process for reducing iron ores or oxides in the manner above referred to in which a small amount of lime is mixed with the powdered coal or coke to assist in removing sulphur. l

The above objects together with others which will be apparent from the drawings and following description, or which may be later referred to, may be attained by carrying out the process of making sponge iron from ores or oxides in manner hereinafter described in detail, reference being made to the accompanying drawings, in which: l

Figure 1 is a perspective view of a hollow briquette or block formed of ore or oxide and a binder;

Fig. 2 a vertical sectional view through a sagger showing a hollow brlquette or block of ores or oxides located therein and the sagger and interior of the briquette filled with powdered carbonaceous material;

Fig. 3 a top plan view of a slightly smaller scale;

Fig. 4 a perspective view of another. shape Aoi' hollow block or brlquette of ores "or oxides and binder; l 4

Fig. 5 a vertical, sectional view through a kiln showing the manner in which the saggers, 'containing the hollow. briquettes and loose carbonaceous material may be stacked therein for carrying out the reduction process;

Fig. 6 a transverse sectional View through a of circular cross sec.-

the filled sagger, on

tion;

Fig. 7 a similar view of a substantially square briquette;

Fig. 8 a transverse sectional view through an oblong, rectangular briquette or block;

Fig. 9 a similar view of a hollow block of hexagonal cross sectional shape; and

Fig. 10 a cross sectional view of still another shape in which the hollow briquette or block f ores or oxides and binder may be made.

Referring first more particularly to Figs. 1 to 3 inclusive and Fig. 5 in which similar numerals refer to similar parts, in carrying out the improved process, a hollow block or briquette as indicated generally at I5 may be formed from a mixture of the ore or oxide to be reduced together with a small amount of a suitable binder.

Either the natural iron ores such as hematite, limonite, magnetite, siderite, gothite, tungite, bog ores, etc. or any iron oxide such as mill scale, flue dust, or other material containing ferric 0X- ide (FezOa), ferroso-ferric oxide (FeaOl) or ferrous oxide (FeO) may be reduced to sponge iron by this process. o

The ore or oxide is first reduced to a powdered condition by grinding or the like and is mixed with a small amount of suitable binder, a 'l1/2% starch solution having been found very satisfactory for this purpose. A suicient amount of the starch solution or other binder to bind the particles of ore or oxide together is mixed with the finely divided ore or oxide and may then be placed in a machine such as a brick machine and extruded through a die to form the hollow briquette or block of ore or oxide indicated in Fig. 1 provided with a plurality of internal openings or passages I6 spaced by partition walls I'I. All of the partition walls I1 as well as the exterior walls I8 of the hollow briquette or block should be formed of such thickness thatheat will pene- Vtrate directly therethrough so as to reduce the ore or oxide of which the briquette or block is formed in the manner hereinafter set forth in detail.

Instead of extruding the mixture of ore or oxide and binder through a die as above described, the hollow block or briquette I5 may be formed by casting, molding or pressing the mixture of finely divided ore or oxide and binder to the desired shape.

This hollow block or briquette of ore or oxide may then be dried and placed Within a sagger or similar container indicated generally at I9 which may be formed of fire clay or other suitable material.

This sagger is preferably of slightly larger cross sectional area than the hollow block or ,therein to fill the space between the exterior walls of the hollow block I5 and the inner walls of the sagger. Powdered coal or coke as indicated at 2| is also placed within the interior openings or passages I6 in the hollow block filling the same as shown in Figs. 2 and 3.

The sagger with theV hollow block of ore or oxide, and powdered coal or coke therein is placed upon the hearth of a furnace, kiln or the like .and preferably closed at its upper end by the cover 22 which may be in the form Yof a fiat slab of any suitable material, and the hollow block of ore or oxide embedded in the-powdered coal or coke within the sagger is then subjected to a suiciently high temperature for a sucient period of time to reduce the ore or oxide to sponge iron, the hollow briquette retaining its form in the re'- duced condition so that a block or briquette of sponge iron is produced which may be easily transported and handled.

The reduction process may be carried out in the conventional type of -kiln indicated generally at 23 in Fig. 5 in which 'case vthe saggers, lled as above described and as illustrated in Figs. 2 and 3, may be stacked in tiers within the kiln as shown in'Fig. 5, the lowermost sagger of each tier resting upon the hearth or.l floor 24 of the kiln, each upper sagger in the tier resting upon the cover or slab 22 of the next lower sagger in the tier.

In order to assist in removing sulphur a small amount of lime may be mixed with the powdered coal or coke, the proportions varying from 3% to 10% of lime, depending upon the materials used,

conditions, etc. y

II the reduction process is carried out in an ordnary kiln, the kiln vis fired as in conventional practice and may be brought up to a temperature of about 2000 F. and held at this temperature for a suicient time to reduce the ores oroxides in the hollow block to sponge iron. At this temperature, the powdered coal or coke surrounding and located within the inte 'or openings or passages of the hollow block of\ re or oxide will be burned producing a reducing atmosphere entirely -surrounding the ore or oxide block or briquette,

the heat entirely penetrating all of the walls thereof so as to reduce the ores or oxides. Re-

gardless of whether the kiln is fired using a ref ducing or oxidizing flame, it will be seen that the ore or oxide block or briquette being entirely surrounded by the burning carbonaceous material, will be maintained undera reducing atmosphere.

'I'he time required forthe reduction of the ore or oxide will vary somewhat with the size of the block, the degree of heat,V the kiln, furnace or other heating chamber in which the reducing process is carried out and other conditions, but after the ore or oxide block has been brought to a temperature of about 2000 F., it' will be reduced within a period of 4 or 5 hours, producing a hollow block or briquette of sponge iron.

Although. a hollow block or briquette of the general form shown in Fig. 1 may be desirable for economic reasons, the invention may be carried out by forming the hollow briquette or block of ore or oxide in various shapes or sizes. For instance in Fig. 4 the hollow block or briquette I5a is ofl smaller cross sectional shape and with I a less number of interior openings or passages IBa. In Fig. -6 is shown a hollow block or briquette I5b in the form of a hollow cylinder with a single central opening or passage IBb and ln Fig. 7 the block I5c isof substantially square cross sectional shape 'with a single interior opening or passage I6c. In Fig. r8 the block I5d is of oblong, rectangular shape with two interior openings or passages IIid. The hollow block orbriquette of ore or oxide may be formed in various other cross sectional shapes such as the hexagon I6e shown in Fig. 9 or the trapezoid I6f sh'own in Fig. 10. In each case, regardless of the size or shape in which the hollow briquette or block of ore is formed the process may be Acarried out in the manner above bdescribed.

I claim:

l. The process of reducing iron oxides which consists Yin .forming a hollow block. consisting of nely divided oxide and a binder, filling the in- .terior and surrounding the exterior of said hollow block with finely divided carbonaceous material, holding the `carbonaceous material in place by an inert casing and subjecting it to suiiicient heat to generate reducing gases within and around the hollow block to substantially entirely reduce the oxides in the block producing a block of metallic iron. g

2. 'I'he process of reducingiron oxides which consists in forming a hollow block consisting of finely divided oxide and a binder, lling the in-` Y terior and surrounding the exterior of said hollow block with finely divided carbonaceous material and lime, holding the carbonaceous material and lime in place by an inert casing and subjecting it'to sufiicient heat to generate reducing gases within and around the hollow. block to substantially entirely reduce the oxides in the block producing a Iblock of metallic iron.

3. The process of reducing iron oxides which consists in forming a hollow block consisting of finely divided oxide and a starch binder, filling the interior and surrounding the exterior of said hollow block with finely divided carbonaceous` material, holding the carbonaceous material in place by an inert casing and subjecting it to sufficient heat to generate reducing gases within and around the hollow block to substantially enterial in place by an inert casing and subjecting it to sufficient' heat to generatereducing gases within and around the hollow block to substantially entirely reduce the oxides in the block producing a block of metallic iron.

5. The process of reducing iron oxides which consists in forming a hollow block consisting ofl finely divided oxide and about a 7% starch solution, filling the interior and surrounding the exterior of said hollow block with carbonaceous material and 3% to 10% lime, holding the carbonaceous material and lime in place by an inert casing, and subjecting it t'o about 2000 F. for a suflicient period of time to reduce the oxide, producing a block of metallic iron.

6. The process of producing a hollow block of metallic iron which consists in forming a hollow block consisting of finely divided iron oxide and\ a binder, filling the interior of said hollow block and surrounding the exterior thereof with car.- bonaceous material, holding the `carbonaceous material in place by an inert casing and subjecting it to sufficient temperature for a suflicient period of time to reduce the oxide to metallic i iron producing a block of metallic iron.

7. The process of. reducing iron oxides which `consists in forming an extruded block consisting of finely divided ore or oxide and abinder.v of such thickness that `heat vcan penetrate therethrough so asto reduce the oxide entirely surrounding all of the exterior surfaces of said block with finely divided carbonaceous material, holding the carbonaceous material in place by. an inert casing andsubjecting it to sufficient heat to generate reducing gases around and through the block to' substantially entirely reduce the oxides in the block to y`metallic iron producing a block of metallic iron.

-,8; The process of reducing iron oxides which ,consists in forming an extruded block consisting of finely divided ore `or oxide and a binder, of suchthickness that heat can penetrate therethrough so as -to reduce the oxide, entirely surrounding al of the exterior surfaces of said block with finely divided'carbonaceous material, holding the carbonaceous material in place by an inert casing and subjecting it'to suttlcient heat to generate reducing gases around and vthrough the block to substantially entirely reduce the oxides in the block to -metallic iron producing a block of metallic iron. x

9. The process of reducing iron oxides which consists in forming an extruded block consisting of finely divided oxide andfsufiicient starch solutionto form a binder, of such thickness that heat can penetrate therethrough so as to reduce the oxide, entirely surrounding all of the exterior surfaces of said block' with finely divided carbonaceous material, holding the carbonaceous material in place by an inert casing and subjecting it to sufficient heat to generate reducing gases around and through the block to substantially entirely reduce the oxides in the block to metallic iron producing a block of metallic iron.

ENOS A. STEWART. 

